N-oxides / Nitroso compounds
N-oxides or amine N-oxides are a class of compounds that contain a nitrogen-oxygen coordinate covalent bond. Nitroso compounds contain nitric oxide group attached to an organic moiety. Almost all amine oxides are prepared by the oxidation of either tertiary aliphatic amines or aromatic N-heterocycles. N-oxides are used as protecting group for amines and as chemical intermediates. Pyrolytic elimination of N-oxides gives alkenes (Cope reaction), reductions lead to amines. They can be used as reoxidants in catalytic oxidations. Long-chain alkyl amine oxides are used as amphoteric surfactants and foam stabilizers. Nitroso compounds can be prepared by the reduction of nitro compounds or by the oxidation of hydroxylamines. Many reactions exist which make use of an intermediate nitroso compound such as Barton reaction and Davis–Beirut reaction, as well as in the synthesis of indoles (Baeyer–Emmerling or Bartoli indole synthesis).